Question 20

Positron-emission tomography is the method of studying the brain that involves an injection of dye into the blood.

Positron-emission tomography (PET) is a neuroimaging technique that requires the injection of a radioactive tracer, which acts similarly to dye, into the bloodstream to visualize brain activity.

A) Computerized axial tomography

Computerized axial tomography (CAT) uses X-rays to create detailed images of the brain but does not involve any injection of dye. Instead, it relies on the differential absorption of X-rays by different tissues, making it distinct from techniques that inject substances into the blood.

B) Positron-emission tomography

Positron-emission tomography (PET) is indeed the correct answer as it involves the injection of a radioactive tracer into the bloodstream. This tracer emits positrons, which are detected by the scanner to produce images that reflect brain activity and metabolism, illustrating its unique methodology.

C) Transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) is a non-invasive procedure that uses magnetic fields to stimulate nerve cells in the brain. It does not involve any injection of dye or tracers, focusing instead on electromagnetic induction to influence brain activity.

D) Magnetoencephalograph

Magnetoencephalography (MEG) measures the magnetic fields produced by neuronal activity in the brain. Like TMS, it is a non-invasive technique that does not use injections of dye or radioactive substances, making it fundamentally different from PET.

Conclusion

Positron-emission tomography is the only method listed that involves the injection of a tracer into the bloodstream to study brain function, which is pivotal for understanding metabolic processes in the brain. All other options either utilize different imaging techniques or are non-invasive methods that do not involve any injections, highlighting PET's unique approach in neuroimaging.